The instant application relates generally to the field of loudspeaker system, and more specifically to a system of horns that are more efficient and matched one to another due to the placement of the components and the configuration of the horns themselves.
The great proliferation of electronic recording and reproduction equipment in the past two decades has led to a variety of theories concerning sound reproduction and an attendant plethora of speaker configurations to reflect theories concerning greater fidelity. Today, speaker enclosures are available in all shapes and sizes, each claiming advantages over the other. Since accurate sound reproduction must cover a range of frequencies from a high frequency to a low frequency, a good loudspeaker system is usually constructed from a number of components ranging from tweeters to mid-range to mid-bass to bass components. It is often the case that a speaker system will sound particularly bright or lively through certain frequency ranges but sound flat or dead in other frequency ranges. Therefore, a speaker system must have its components tuned or matched to one another in order to effect smooth transitions between components as frequency ranges change.
More specifically, a loudspeaker system, especially those used in the commercial presentation of live music, often emphasizes the heavy lower bass frequencies at the expense of the response of the entire system. This requires heavy, lower efficiency speaker cones which slow down the response dynamics of the speaker and require much more amplification. Therefore, this mode of presentation does not balance well with the higher frequency speakers in the system. Many designs have been tried in an attempt to overcome this problem, however, the end result is always a compromise and the prior art problems remain.
A further problem involved in the bass response of public address and loudspeaker systems is the acoustical impedance seen by the driven diaphram in a front loaded horn with a rear enclosure which creates a compression chamber that effects the motion of the diaphram in certain modes of response.
These two prior art problems are addressed and solved in the device according to the instant application by providing a woofer with a front loaded horn and a rear loaded folded horn which is responsive to lower frequencies so that the diaphram motion is in linear phase alignment, which can be defined as a balance between the positive impedance encountered by the front loading and the negative impedance encountered by the rear loading of the diaphram. Furthermore, the lower limits of the front loaded horn are equal to the upper limits of the low bass horn which accesses the rear side of the diaphram. Thus, one acoustic driver drives both the mid-bass horn and the folded low bass horn, thereby eliminating the problems encountered in prior art devices such as non-linearity and non-compatibility. Furthermore, the close coupling of the mid-bass horn mouths enhance the overall function of the lower frequency range of components of the speaker system.
The reproduction of mid-range frequency sound also presents a series of unique problems. Most notable is the bell resonance effect so common to traditional mid-range speaker horns, such as those often seen in public address systems. Often the horn itself will resonate with a single frequency thus producing an interference tone, due to a harmonic response by the horn to the single frequency. Furthermore, there is often a problem in high efficiency sound dispersion with the molded contiguous surfaces associated with the conventional horn driven by a mid-range driver. These problems are solved in the instant application by the provision of the elliptically mouthed, stepped mid-range speaker that provides an acoustic choke to the bell resonance effect and increases radial dispersion of the sound by providing a series of elliptical steps that each become a horn mouth for a certain frequency associated therewith, thereby eliminating bell resonance and increasing mid-range horn efficiency and dispersion.
A final problem encountered in prior art devices and solved by the device according to the instant application is the matching of the high frequency response to the rest of the components so that the high frequencies are not overpowered and muted by the over amplification of the lower frequency ranges. This problem is solved by placing the tweeters inside the mid-bass horn in a precise relationship with the mid-bass driver thereby taking advantage of the sound dispersions surfaces contained therein and providing a means to easily match the power afforded to the various frequency ranges.
The prior art of which applicant is aware that would appear to be germane to the patent process is as follows U.S. Pat. Nos.: 2,808,121, Goettner 2,975,852, Chave 3,729,061, Tamura 4,119,799, Merlino 4,138,594, Klipsch 4,325,454 Humphrey.
Of the prior art citations, the patent to Chave is of interest since he teaches the use of loading a folded bass horn from the diaphram of a driver which also loads an acoustic enclosure from the front. The device according to the instant application is distinguished in that it provides a series of compression chambers and compression baffles which facilitate the excitement of the column air contained within the bass horn chamber. Furthermore, the patent to Chave exhibits a meandering convoluted path for the sound to travel through the folded horn section of the bass speaker enclosures which results in acoustical muting of the sound rather than an acoustical boost which is the effect of the device according to the instant application.
The patents to Klipsch and Tamura are of interest since they both teach the use of redirecting the lower frequencies through a cabinet enclosure to invert the phase and enhance the resultant sound. However, neither of the aformentioned citations provide baffle plates to define acoustic compression chambers to boost lower frequency resonance. Furthermore, the interior curved surfaces of the folded base horn enclosure in the instant invention provide advantages when trying to excite the column of air contained thereon.
Further distinguishing characteristics of the instant invention will become apparent when considering the detailed specifications to follow.